Whats a good economical way to test the electricity on a circuit?

Relax. The one thing we know for sure is its noisy, dirty, whatever you want to call it. The other thing we know for sure is if you do find something to measure and quantify this it will do absolutely nothing for you. Because we already know its noisy, and we already know what to do about it. Actually its even worse than that. Because if you measure something then that's what you think needs to be fixed, and all it does is set you up for someone's marketing story they want to use to get your money. 

So what you do instead is talk to people, read reviews, listen to different things, and buy whatever improves the sound. Power cord, fuse, conditioner, TA-102 tape, TC, outlet covers, whatever. All these things actually work and can hugely improve performance. I have no idea whatsoever how they made the AC sine wave look different on a scope. Nor do I care. Nor should you.

Almost forgot! There is one free and very simple test you can perform to hear for yourself just how much noise there is in your AC. Get your system nicely warmed up. Listen to your favorite music. Go to your panel, flip off as many circuit breakers as you can. Ideally everything but what's needed for the system, but for sure do water heater, stove, refrigerator, spare rooms, stuff like that. Go back and play that same music again. The huge improvement you just heard- blacker background, clearer details, improved dynamics, with less grain and glare - is all due to the reduction in noise from separating the system from all those other circuits. You will hear it. And once you do, you will understand why you do not need no meter. Because you have something better: ears. 

Go and listen. You will see.

I get what your all saying.. makes sense.. and not sure if im coming off nutty but i am pretty relaxed.. just wanted to play around with some measurements.. especially to see how well these PC, conditioners, etc are working.. Thinking of putting a dedicated line in.. aside from ears.. but just wanted to play around with the idea.. so if i shut off everything.. except breaker line to audio system.. that would get the same results as a dedicated line?

Now that you know your VAC is "Dirty", what you gonna do about it?

I have a good supply, very seldom have outages, very seldom have brownouts, and we haven't had spikes or over voltage for over 30 years.
PG&E went from 8k lines to 20k lines, 35 years ago. A lot of problems went away. Constant Power supplies issues, all around us.

PC especially use to lose their power supplies. One in maybe in 30 years now, from 1 a year. You had to run a PS backup, if you were running a server...

We have smart meters, now too. There is a lot more information there than you might think..

What do you as an owner of expensive equipment, do to protect your gear?

I use something that maintains, the voltage at 120 VAC on the button.
Surge protection, filters above 40 khz, and 20khz. Good copper inlets and outlets on the device. The lowest noise level I can achieve (hum). The quickest response time in the event there is a problem.

There is a few more features, but maintaining the voltage, is one of the best things you can do to increase gear life. Mine cost 300.00 usd or close, and about 6-10 dollars in stuff to quiet the mechanical hum, to practically zip...

Regards